(1) Field of the Invention
The present invention relates to a hermetic type compressor mainly used in an air conditioner.
(2) Description of the Prior Art
In a conventional hermetic type compressor, especially one-cylinder type rotary compressor, an induction motor is employed in many cases. A rotor of the motor is made of iron plates firmed with aluminum; therefore, even though the rotor is hollow, a portion of the rotor is not displaced.
Accordingly, in the case of the conventional hermetic type compressor, its main shaft is made short and a portion of the rotor is made hollow in many cases.
However, recently, in order to realize a high efficiency motor, the rotor of the motor is made of laminated iron plates and permanent magnets are embedded inside thereof. In this rotor, embedded pins are caulked from opposite end surfaces, thereby holding the laminated iron plates.
In the case of a motor whose rotor is made of laminated iron plates in this manner and a portion thereof is hollow, when a force such as a centrifugal force acting on a balance weight is applied to the laminated iron plates, a portion of the laminated iron plates is displaced in the radial direction in some cases. If the laminated iron plates are displaced in the radial direction, the rotor comes into contact with a stator, thereby causing problems such as increase of sliding loss, the resultant input increase, and damages to a compressor mechanism caused by the particles produced by such contact.
Further, refrigerant gas compressed in the hermetic type compressor is discharged into an internal space of a hermetic container from a discharge portion of the compressor mechanism (e.g., a discharge hole of an upper bearing) and then, the refrigerant gas passes through a clearance between the stator and the rotor and a clearance between the inner wall of hermetic container and the stator, and is discharged into a refrigeration cycle from a discharge pipe through the space above the motor. A large amount of lubricant oil is included in the refrigerant gas discharged from the compressor mechanism, and if the oil is circulated through the refrigeration cycle together with the refrigerant gas, efficiency of the refrigeration cycle (coefficient of performance) is decreased. In the case of the room air conditioner, if the amount of lubricant oil exceeds 0.1 5 wt % (weight percentage) of the circulating amount of refrigerant, the performance of refrigeration cycle is deteriorated. Therefore, it is necessary to separate the oil within the hermetic container before the refrigerant gas is discharged from the discharge pipe. To achieve this objective, i.e., to separate the oil from the refrigerant gas, the conventional hermetic type compressors employ a disk mounted to an upper portion of the rotor that shakes off oil mist by a centrifugal force, or a large volume upper space above the motor to reduce the speed of gas flow, thereby separating the oil.
Thereupon, it is an object of the present invention to provide a hermetic type compressor in which even if a centrifugal force is applied to a balance weight at the time of high speed operation, laminated iron plates of a rotor are not displaced in the radical direction, and an excellent driving state can be kept.
It is another object of the invention to provide a hermetic type compressor in which a stirring effect of a rotor does not exert an influence upon an upper space above the motor, thereby, the amount of oil discharged from a discharge pipe is reduced, and the entire height of the hermetic type compressor can easily be accomodated in, for example, an air conditioner.
According to a first aspect of the present invention, there is provided a hermetic type compressor comprising a hermetic container in which a compressor mechanism and a motor are accomodated, and a rotor of the motor is comprised of laminated iron plates in which permanent magnets are embedded, and a main shaft of the compressor mechanism is inserted into the rotor over its entire length as a common shaft thereof.
According to this first aspect, since the main shaft of the compressor mechanism is inserted into the rotor over its entire length as its common shaft, even if a centrifugal force is applied to a balance weight at the high speed operation, the laminated iron plates of rotor are not displaced in the radical direction, and, therefore, an excellent driving state can be kept.
According to a second aspect of the present invention, in the above hermetic type compressor of the first aspect, large and small balance weights are mounted to opposite end surfaces of the rotor, respectively.
If the balance weights are provided as in the second aspect, even if a large centrifugal force is applied to a portion of the laminated iron plates of the rotor, although the laminated iron plates of the rotor are prone to be displaced in the radical direction, such displacement problem can be prevented, and a excellent driving state can be kept.
According to a third aspect, there is provided a hermectic type compressor comprising a hermectic container having an internal space to which a discharge gas pressure applies, a compressor mechanism provided in a lower portion of the hermectic container, a motor provided in an upper portion of the hermectic container, and a discharge pipe provided in the upper portion of the hermectic container, and a cover is mounted to the upper portion of a coil end of a stator of the motor to cover a space above the rotor of the motor.
According to the third aspect, the flow of refrigerant which has passed through a clearance between the rotor and the stator is blocked by the cover and is bent substantially perpendicularly; and the refrigerant passes through the coil end and goes outside of the stator. Therefore, when the refrigerant passes through the coil end, oil adheres to the coil wires and is separated from the refrigerant, and it is possible to prevent the oil from being discharged out from the hermectic container. Further, since space in which the rotor rotates is completely isolated from an upper space of the container by the cover, a stirring effect by the rotor 32 does not exert an influence upon the upper space. Further, since oil mist does not directly reach the discharge pipe, the amount of oil discharging from the discharge pipe is remarkably reduced. Yet further, it is possible to reduce the necessary volume of upper space above the motor by mounting the cover, the entire height of the hermectic type compressor can be shortened, and, thereby, it is possible to provide a hermectic type compressor which can easily be accomodated into, for example, an air conditioner.